The present invention relates to an information retrieval system and, more particularly, to an information retrieval system equipped with a randomly-accessible memory medium such as a video disk.
Recently, electronic devices called electronic dictionaries have become available on the market. These electronic dictionaries require efficient and rapid retrieval of word information stored in a ROM. An example of such electronic dictionaries is disclosed in Levy U.S. Pat. No. 4,158,236, June 12, 1979, "ELECTRONIC DICTIONARY AND LANGUAGE INTERPRETER". The disclosure of this patent is incorporated herein by reference.
However, the capacity of a ROM is rather small.
The present invention is concerned with the use of a video storage medium, such as a video disk, as part of an improved information retrieval system. A video storage medium allows large quantities of information to be stored and rapidly accessed. The information may be stored in the form of video data, in which case the information can be displayed on a video monitor.
In a video disk, information such as word information is memorized in the form of digital codes. Careful consideration should be directed to the problem that dust on the video disk may cause errors in reading out information from the video disk.
Further, when the video disk provides a still picture, the same tracks of the video disk are repeatedly traced, so that it was impossible to speak, as one reads, with the word information. This would be a disadvantage for the electronic dictionary.
Since, in a single track of the video disk, the visual signals forming a single, still television picture, the aural signals and the address signals are superimposed, the repetition of the tracing on the same single track provides the single still television picture. However, because the round length of the single track can be traced for a very short time, about 30.sup.-1 to 60.sup.-1 sec., the data of the aural signals developed in accordance with the tracing of the single track are too small to provide pronunciation, as one reads, with the data. The reproduction of the data therefore may merely cause noise.
A system of the present invention is preferably designed to avoid the above discussed problems.